Explanation on Faber’s part was short and simple. The nephew whom he designed as the heir to his wealth had largely outstripped the liberal allowance made to him, had incurred heavy debts; and in order to extricate himself from the debts, had plunged into ruinous speculations. Faber had come back to England to save his heir from prison or outlawry, at the expense of more than three-fourths of the destined inheritance. To add to all, the young man had married a young lady without fortune; the uncle only heard of this marriage on arriving in England. The spendthrift was hiding from his creditors in the house of his father-in-law, in one of the western counties. Faber there sought him; and on becoming acquainted with his wife, grew reconciled to the marriage, and formed hopes of his nephew’s future redemption. He spoke, indeed, of the young wife with great affection. She was good and sensible; willing and anxious to encounter any privation by which her husband might reprieve the effects of his folly. “So,” said Faber, “on consultation with this excellent creature—for my poor nephew is so broken down by repentance, that others must think for him how to exalt repentance into reform—my plans were determined. I shall remove my prodigal from all scenes of temptation. He has youth, strength, plenty of energy, hitherto misdirected. I shall take him from the Old World into the New. I have decided on Australia. The fortune still left to me, small here, will be ample capital there. It is not enough to maintain us separately, so we must all live together. Besides, I feel that, though I have neither the strength or the experience which could best serve a young settler on a strange soil, still, under my eye, my poor boy will be at once more prudent and more persevering. We sail next week.”

Faber spoke so cheerfully that I knew not how to express compassion; yet, at his age, after a career of such prolonged and distinguished labour, to resign the ease and comforts of the civilized state for the hardships and rudeness of an infant colony, seemed to me a dreary prospect; and, as delicately, as tenderly as I could to one whom I loved and honoured as a father, I placed at his disposal the fortune which, in great part, I owed to him,—pressing him at least to take from it enough to secure to himself, in his own country, a home suited to his years and worthy of his station. He rejected all my offers, however earnestly urged on him, with his usual modest and gentle dignity; and assuring me that he looked forward with great interest to a residence in lands new to his experience, and affording ample scope for the hardy enjoyments which had always most allured his tastes, he hastened to change the subject.

“And who, think you, is the admirable helpmate my scape-grace has had the saving good luck to find? A daughter of the worthy man who undertook the care of poor Dr. Lloyd’s orphans,—the orphans who owed so much to your generous exertions to secure a provision for them; and that child, now just risen from her father’s grave, is my pet companion, my darling ewe lamb,—Dr. Lloyd’s daughter Amy.”

Here the child joined us, quickening her pace as she recognized the old man, and nestling to his side as she glanced wistfully towards myself. A winning, candid, lovable child’s face, somewhat melancholy, somewhat more thoughtful than is common to the face of childhood, but calm, intelligent, and ineffably mild. Presently she stole from the old man, and put her hand in mine.

“Are you not the kind gentleman who came to see him that night when he passed away from us, and who, they all say at home, was so good to my brothers and me? Yes, I recollect you now.” And she put her pure face to mine, wooing me to kiss it.

I kind! I good! I—I! Alas! she little knew, little guessed, the wrathful imprecation her father had bequeathed to me that fatal night!

I did not dare to kiss Dr. Lloyd’s orphan daughter, but my tears fell over her hand. She took them as signs of pity, and, in her infant thankfulness, silently kissed me.

“Oh, my friend!” I murmured to Faber, “I have much that I yearn to say to you—alone—alone! Come to my house with me, be at least my guest as long as you stay in this town.”

“Willingly,” said Faber, looking at me more intently than he had done before, and with the true eye of the practised Healer, at once soft and penetrating.

He rose, took my arm, and whispering a word in the ear of the little girl, she went on before us, turning her head, as she gained the gate, for another look at her father’s grave. As we walked to my house, Julius Faber spoke to me much of this child. Her brothers were all at school; she was greatly attached to his nephew’s wife; she had become yet more attached to Faber himself, though on so short an acquaintance; it had been settled that she was to accompany the emigrants to Australia.

“There,” said he, “the sum, that some munificent, but unknown friend of her father has settled on her, will provide her no mean dower for a colonist’s wife, when the time comes for her to bring a blessing to some other hearth than ours.” He went on to say that she had wished to accompany him to L——, in order to visit her father’s grave before crossing the wide seas; “and she has taken such fond care of me all the way, that you might fancy I were the child of the two. I come back to this town, partly to dispose of a few poor houses in it which still belong to me, principally to bid you farewell before quitting the Old World, no doubt forever. So, on arriving to-day, I left Amy by herself in the churchyard while I went to your house, but you were from home. And now I must congratulate you on the reputation you have so rapidly acquired, which has even surpassed my predictions.”

“You are aware,” said I, falteringly, “of the extraordinary charge from which that part of my reputation dearest to all men has just emerged!”

He had but seen a short account in a weekly journal, written after my release. He asked details, which I postponed.

Reaching my home, I hastened to provide for the comfort of my two unexpected guests; strove to rally myself, to be cheerful. Not till night, when Julius Faber and I were alone together, did I touch on what was weighing at my heart. Then, drawing to his side, I told him all,—all of which the substance is herein written, from the deathscene in Dr. Lloyd’s chamber to the hour in which I had seen Dr. Lloyd’s child at her father’s grave. Some of the incidents and conversations which had most impressed me I had already committed to writing, in the fear that, otherwise, my fancy might forge for its own thraldom the links of reminiscence which my memory might let fall from its chain. Faber listened with a silence only interrupted by short pertinent questions; and when I had done, he remained thoughtful for some moments; then the great physician replied thus:—

“I take for granted your conviction of the reality of all you tell me, even of the Luminous Shadow, of the bodiless Voice; but, before admitting the reality itself, we must abide by the old maxim, not to accept as cause to effect those agencies which belong to the Marvellous, when causes less improbable for the effect can be rationally conjectured. In this case are there not such causes? Certainly there are—”

“There are?”

“Listen; you are one of those men who attempt to stifle their own imagination. But in all completed intellect, imagination exists, and will force its way; deny it healthful vents, and it may stray into morbid channels. The death-room of Dr. Lloyd deeply impressed your heart, far more than your pride would own. This is clear from the pains you took to exonerate your conscience, in your generosity to the orphans. As the heart was moved, so was the imagination stirred; and, unaware to yourself, prepared for much that subsequently appealed to it. Your sudden love, conceived in the very grounds of the house so associated with recollections in themselves strange and romantic; the peculiar temperament and nature of the girl to whom your love was attracted; her own visionary beliefs, and the keen anxiety which infused into your love a deeper poetry of sentiment,—all insensibly tended to induce the imagination to dwell on the Wonderful; and, in overstriving to reconcile each rarer phenomenon to the most positive laws of Nature, your very intellect could discover no solution but in the Preternatural.

“You visit a man who tells you he has seen Sir Philip Derval’s ghost; on that very evening, you hear a strange story, in which Sir Philip’s name is mixed up with a tale of murder, implicating two mysterious pretenders to magic,—Louis Grayle and the Sage of Aleppo. The tale so interests your fancy that even the glaring impossibility of a not unimportant part of it escapes your notice,—namely, the account of a criminal trial in which the circumstantial evidence was more easily attainable than in all the rest of the narrative, but which could not legally have taken place as told. Thus it is whenever the mind begins, unconsciously, to admit the shadow of the Supernatural; the Obvious is lost to the eye that plunges its gaze into the Obscure. Almost immediately afterwards you become acquainted with a young stranger, whose traits of character interest and perplex, attract yet revolt you. All this time you are engaged in a physiological work which severely tasks the brain, and in which you examine the intricate question of soul distinct from mind.

“And, here, I can conceive a cause deep-hid amongst what metaphysicians would call latent associations, for a train of thought which disposed you to accept the fantastic impressions afterwards made on you by the scene in the Museum and the visionary talk of Sir Philip Derval. Doubtless, when at college you first studied metaphysical speculation you would have glanced over Beattie’s ‘Essay on Truth’ as one of the works written in opposition to your favourite, David Hume.”

“Yes, I read the book, but I have long since forgotten its arguments.”

“Well in that essay, Beattie(1) cites the extraordinary instance of Simon Browne, a learned and pious clergyman, who seriously disbelieved the existence of his own soul; and imagined that, by interposition of Divine power, his soul was annulled, and nothing left but a principle of animal life, which he held in common with the brutes! When, years ago, a thoughtful imaginative student, you came on that story, probably enough you would have paused, revolved in your own mind and fancy what kind of a creature a man might be, if, retaining human life and merely human understanding, he was deprived of the powers and properties which reasoners have ascribed to the existence of soul. Something in this young man, unconsciously to yourself, revives that forgotten train of meditative ideas. His dread of death as the final cessation of being, his brute-like want of sympathy with his kind, his incapacity to comprehend the motives which carry man on to scheme and to build for a future that extends beyond his grave,—all start up before you at the very moment your reason is overtasked, your imagination fevered, in seeking the solution of problems which, to a philosophy based upon your system, must always remain insoluble. The young man’s conversation not only thus excites your fancies,—it disturbs your affections. He speaks not only of drugs that renew youth, but of charms that secure love. You tremble for your Lilian while you hear him! And the brain thus tasked, the imagination thus inflamed, the heart thus agitated, you are presented to Sir Philip Derval, whose ghost your patient had supposed he saw weeks ago.

“This person, a seeker after an occult philosophy, which had possibly acquainted him with some secrets in nature beyond the pale of our conventional experience, though, when analyzed, they might prove to be quite reconcilable with sober science, startles you with an undefined mysterious charge against the young man who had previously seemed to you different from ordinary mortals. In a room stored with the dead things of the brute soulless world, your brain becomes intoxicated with the fumes of some vapour which produces effects not uncommon in the superstitious practices of the East; your brain, thus excited, brings distinctly before you the vague impressions it had before received. Margrave becomes identified with the Louis Grayle of whom you had previously heard an obscure and, legendary tale, and all the anomalies in his character are explained by his being that which you had contended, in your physiological work, it was quite possible for man to be,—namely, mind and body without soul! You were startled by the monster which man would be were your own theory possible; and in order to reconcile the contradictions in this very monster, you account for knowledge, and for powers that mind without soul could not have attained, by ascribing to this prodigy broken memories of a former existence, demon attributes from former proficiency in evil magic. My friend, there is nothing here which your own study of morbid idiosyncracies should not suffice to solve.”

“So, then,” said I, “you would reduce all that have affected my senses as realities into the deceit of illusions? But,” I added, in a whisper, terrified by my own question, “do not physiologists agree in this: namely, that though illusory phantasms may haunt the sane as well as the insane, the sane know that they are only illusions, and the insane do not.”

“Such a distinction,” answered Faber, “is far too arbitrary and rigid for more than a very general and qualified acceptance. Muller, indeed, who is perhaps the highest authority on such a subject, says, with prudent reserve, ‘When a person who is not insane sees spectres and believes, them to be real, his intellect must be imperfectly exercised.‘(2) He would, indeed, be a bold physician who maintained that every man who believed he had really seen a ghost was of unsound mind. In Dr. Abercrombie’s interesting account of spectral illusions, he tells us of a servant-girl who believed she saw, at the foot of her bed, the apparition of Curran, in a sailor’s jacket and an immense pair of whiskers.(3) No doubt the spectre was an illusion, and Dr. Abercrombie very ingeniously suggests the association of ideas by which the apparition was conjured up with the grotesque adjuncts of the jacket and the whiskers; but the servant-girl, in believing the reality of the apparition, was certainly not insane. When I read in the American public journals(4) of ‘spirit manifestations,’ in which large numbers of persons, of at least the average degree of education, declare that they have actually witnessed various phantasms, much more extraordinary than all which you have confided to me, and arrive, at once, at the conclusion that they are thus put into direct communication with departed souls, I must assume that they are under an illusion; but I should be utterly unwarranted in supposing that, because they credited that illusion, they were insane. I should only say with Muller, that in their reasoning on the phenomena presented to them, ‘their intellect was imperfectly exercised.’ And an impression made on the senses, being in itself sufficiently rare to excite our wonder, may be strengthened till it takes the form of a positive fact, by various coincidences which are accepted as corroborative testimony, yet which are, nevertheless, nothing more than coincidences found in every day matters of business, but only emphatically noticed when we can exclaim, ‘How astonishing!’ In your case such coincidences have been, indeed, very signal, and might well aggravate the perplexities into which your reason was thrown. Sir Philip Derval’s murder, the missing casket, the exciting nature of the manuscript, in which a superstitious interest is already enlisted by your expectation to find in it the key to the narrator’s boasted powers, and his reasons for the astounding denunciation of the man whom you suspect to be his murderer,—in all this there is much to confirm, nay, to cause, an illusion; and for that very reason, when examined by strict laws of evidence, in all this there is but additional proof that the illusion was—only illusion. Your affections contribute to strengthen your fancy in its war on your reason. The girl you so passionately love develops, to your disquietude and terror, the visionary temperament which, at her age, is ever liable to fantastic caprices. She hears Margrave’s song, which you say has a wildness of charm that affects and thrills even you. Who does not know the power of music? and of all music, there is none so potential as that of the human voice. Thus, in some languages, charm and song are identical expressions; and even when a critic, in our own sober newspapers, extols a Malibran or a Grisi, you may be sure that he will call her ‘enchantress.’ Well, this lady, your betrothed, in whom the nervous system is extremely impressionable, hears a voice which, even to your ear, is strangely melodious, and sees a form and face which, even to your eye, are endowed with a singular character of beauty. Her fancy is impressed by what she thus hears and sees; and impressed the more because, by a coincidence not very uncommon, a face like that which she beholds has before been presented to her in a dream or a revery. In the nobleness of genuine, confiding, reverential love, rather than impute to your beloved a levity of sentiment that would seem to you a treason, you accept the chimera of ‘magical fascination.’ In this frame of mind you sit down to read the memoir of a mystical enthusiast. Do you begin now to account for the Luminous Shadow? A dream! And a dream no less because your eyes were open and you believed yourself awake. The diseased imagination resembles those mirrors which, being themselves distorted, represent distorted pictures as correct.

“And even this Memoir of Sir Philip Derval’s—can you be quite sure that you actually read the part which relates to Haroun and Louis Grayle? You say that, while perusing the manuscript, you saw the Luminous Shadow, and became insensible. The old woman says you were fast asleep. May you not really have fallen into a slumber, and in that slumber have dreamed the parts of the tale that relate to Grayle,—dreamed that you beheld the Shadow? Do you remember what is said so well by Dr. Abercrombie, to authorize the explanation I suggest to you: ‘A person under the influence of some strong mental impression falls asleep for a few seconds, perhaps without being sensible of it: some scene or person appears in a dream, and he starts up under the conviction that it was a spectral appearance.’” (5)

“But,” said I, “the apparition was seen by me again, and when, certainly, I was not sleeping.”

“True; and who should know better than a physician so well read as yourself that a spectral illusion once beheld is always apt to return again in the same form? Thus, Goethe was long haunted by one image,—the phantom of a flower unfolding itself, and developing new flowers.(6) Thus, one of our most distinguished philosophers tells us of a lady known to himself, who would see her husband, hear him move and speak, when he was not even in the house.(7) But instances of the facility with which phantasms, once admitted, repeat themselves to the senses, are numberless. Many are recorded by Hibbert and Abercrombie, and every physician in extensive practice can add largely, from his own experience, to the list. Intense self-concentration is, in itself, a mighty magician. The magicians of the East inculcate the necessity of fast, solitude, and meditation for the due development of their imaginary powers. And I have no doubt with effect; because fast, solitude, and meditation—in other words, thought or fancy intensely concentred—will both raise apparitions and produce the invoker’s belief in them. Spinello, striving to conceive the image of Lucifer for his picture of the Fallen Angels, was at last actually haunted by the Shadow of the Fiend. Newton himself has been subjected to a phantom, though to him, Son of Light, the spectre presented was that of the sun! You remember the account that Newton gives to Locke of this visionary appearance. He says that ‘though he had looked at the sun with his right eye only, and not with the left, yet his fancy began to make an impression upon his left eye as well as his right; for if he shut his right and looked upon the clouds, or a book, or any bright object with his left eye, he could see the sun almost as plain as with the right, if he did but intend his fancy a little while on it;’ nay, ‘for some months after, as often as he began to meditate on the phenomena, the spectrum of the sun began to return, even though he lay in bed at midnight, with his curtains drawn!’ Seeing, then, how any vivid impression once made will recur, what wonder that you should behold in your prison the Shining Shadow that had first startled you in a wizard’s chamber when poring over the records of a murdered visionary? The more minutely you analyze your own hallucinations—pardon me the word—the more they assume the usual characteristics of a dream; contradictory, illogical, even in the marvels they represent. Can any two persons be more totally unlike each other, not merely as to form and years, but as to all the elements of character, than the Grayle of whom you read, or believe you read, and the Margrave in whom you evidently think that Grayle is existent still? The one represented, you say, as gloomy, saturnine, with vehement passions, but with an original grandeur of thought and will, consumed by an internal remorse; the other you paint to me as a joyous and wayward darling of Nature, acute yet frivolous, free from even the ordinary passions of youth, taking delight in innocent amusements, incapable of continuous study, without a single pang of repentance for the crimes you so fancifully impute to him. And now, when your suspicions, so romantically conceived, are dispelled by positive facts, now, when it is clear that Margrave neither murdered Sir Philip Derval nor abstracted the memoir, you still, unconsciously to yourself, draw on your imagination in order to excuse the suspicion your pride of intellect declines to banish, and suppose that this youthful sorcerer tempted the madman to the murder, the woman to the theft—”

“But you forget the madman said ‘that he was led on by the Luminous Shadow of a beautiful youth,’ that the woman said also that she was impelled by some mysterious agency.”

“I do not forget those coincidences; but how your learning would dismiss them as nugatory were your imagination not disposed to exaggerate them! When you read the authentic histories of any popular illusion, such as the spurious inspirations of the Jansenist Convulsionaries, the apparitions that invaded convents, as deposed in the trial of Urbain Grandier, the confessions of witches and wizards in places the most remote from each other, or, at this day, the tales of ‘spirit-manifestation’ recorded in half the towns and villages of America,—do not all the superstitious impressions of a particular time have a common family likeness? What one sees, another sees, though there has been no communication between the two. I cannot tell you why these phantasms thus partake of the nature of an atmospheric epidemic; the fact remains incontestable. And strange as may be the coincidence between your impressions of a mystic agency and those of some other brains not cognizant of the chimeras of your own, still, is it not simpler philosophy to say, ‘They are coincidences of the same nature which made witches in the same epoch all tell much the same story of the broomsticks they rode and the sabbats at which they danced to the fiend’s piping,’ and there leave the matter, as in science we must leave many of the most elementary and familiar phenomena inexplicable as to their causes,—is not this, I say, more philosophical than to insist upon an explanation which accepts the supernatural rather than leave the extraordinary unaccounted for?”

“As you speak,” said I, resting my downcast face upon my hand, “I should speak to any patient who had confided to me the tale I have told to you.”

“And yet the explanation does not wholly satisfy you? Very likely: to some phenomena there is, as yet, no explanation. Perhaps Newton himself could not explain quite to his own satisfaction why he was haunted at midnight by the spectrum of a sun; though I have no doubt that some later philosopher whose ingenuity has been stimulated by Newton’s account, has, by this time, suggested a rational solution of that enigma.(8) To return to your own case. I have offered such interpretations of the mysteries that confound you as appear to me authorized by physiological science. Should you adduce other facts which physiological science wants the data to resolve into phenomena always natural, however rare, still hold fast to that simple saying of Goethe: ‘Mysteries are not necessarily miracles.’ And if all which physiological science comprehends in its experience wholly fails us, I may then hazard certain conjectures in which, by acknowledging ignorance, one is compelled to recognize the Marvellous (for as where knowledge enters, the Marvellous recedes, so where knowledge falters, the Marvellous advances); yet still, even in those conjectures, I will distinguish the Marvellous from the Supernatural. But, for the present, I advise you to accept the guess that may best quiet the fevered imagination which any bolder guess would only more excite.”

“You are right,” said I, rising proudly to the full height of my stature, my head erect and my heart defying. “And so let this subject be renewed no more between us. I will brood over it no more myself. I regain the unclouded realm of my human intelligence; and, in that intelligence, I mock the sorcerer and disdain the spectre.”

(1) Beattie’s “Essay on Truth,” part i. c. ii. 3. The story of Simon Browne is to be found in “The Adventurer.”

(2) Miller’s Physiology of the Senses, p. 394.

(3) Abercrombie on the Intellectual Powers, p. 281. (15th edition.)

(4) At the date of Faber’s conversation with Allen Fenwick, the (so-called) spirit manifestations had not spread from America over Europe. But if they had, Faber’s views would, no doubt, have remained the same.

(5) Abercrombie on the Intellectual Powers, p. 278. (15th edition.)

This author, not more to be admired for his intelligence than his candour, and who is entitled to praise for a higher degree of original thought than that to which he modestly pretends, relates a curious anecdote illustrating “the analogy between dreaming and spectral illusion, which he received from the gentleman to which it occurred,—an eminent medical friend:” “Having sat up late one evening, under considerable anxiety for one of his children, who was ill, he fell asleep in his chair, and had a frightful dream, in which the prominent figure was an immense baboon. He awoke with the fright, got up instantly, and walked to a table which was in the middle of the room. He was then quite awake, and quite conscious of the articles around him; but close by the wall in the end of the apartment he distinctly saw the baboon making the same grimaces which he had seen in his dreams; and this spectre continued visible for about half a minute.” Now, a man who saw only a baboon would be quite ready to admit that it was but an optical illusion; but if, instead of a baboon, he had seen an intimate friend, and that friend, by some coincidence of time, had died about that date, he would be a very strong-minded man if he admitted for the mystery of seeing his friend the same natural solution which he would readily admit for seeing a baboon.

(6) See Muller’s observations on this phenomenon, “Physiology of the Senses,” Baley’s translation, p. 1395.

(7) Sir David Brewster’s Letters on Natural Magic, p. 39.

(8) Newton’s explanation is as follows: “This story I tell you to let you understand, that in the observation related by Mr. Boyle, the man’s fancy probably concurred with the impression made by the sun’s light to produce that phantasm of the sun which he constantly saw in bright objects, and so your question about the cause of this phantasm involves another about the power of the fancy, which I must confess is too hard a knot for me to untie. To place this effect in a constant motion is hard, because the sun ought then to appear perpetually. It seems rather to consist in a disposition of the sensorium to move the imagination strongly, and to be easily moved both by the imagination and by the light as often as bright objects are looked upon.”—Letter from Sir I. Newton to Locke, Lord Kinq’s Life of Locke, vol. i. pp. 405-408.

Dr. Roget (Animal and Vegetable Physiology considered with reference to Natural Theology, “Bridgewater Treatise,” pp. 524, 525) thus refers to this phenomenon, which he states “all of us may experience “:—

“When the impressions are very vivid” (Dr. Roget is speaking of visual impressions), “another phenomenon often takes place,—namely, their subsequent recurrence after a certain interval, during which they are not felt, and quite independently of any renewed application of the cause which had originally excited them.” (I mark by italics the words which more precisely coincide with Julius Faber’s explanations.) “If, for example, we look steadfastly at the sun for a second or two, and then immediately close our eyes, the image, or spectrum, of the sun remains for a long time present to the mind, as if the light were still acting on the retina. It then gradually fades and disappears; but if we continue to keep the eyes shut, the same impression will, after a certain time, recur, and again vanish: and this phenomenon will be repeated at intervals, the sensation becoming fainter at each renewal. It is probable that these reappearances of the image, after the light which produced the original impression has been withdrawn, are occasioned by spontaneous affections of the retina itself which are conveyed to the sensorium. In other cases, where the impressions are less strong, the physical changes producing these changes are perhaps confined to the sensorium.”

It may be said that there is this difference between the spectrum of the sun and such a phantom as that which perplexed Allen Fenwick,—namely, that the sun has been actually beheld before its visionary appearance can be reproduced, and that Allen Fenwick only imagines he has seen the apparition which repeats itself to his fancy. “But there are grounds for the suspicion” (says Dr. Hibbert, “Philosophy of Apparitions,” p. 250), “that when ideas of vision are vivified to the height of sensation, a corresponding affection of the optic nerve accompanies the illusion.” Muller (“Physiology of the Senses,” p. 1392, Baley’s translation) states the same opinion still more strongly; and Sir David Brewster, quoted by Dr. Hibbert (p. 251) says: “In examining these mental impressions, I have found that they follow the motions of the eyeball exactly like the spectral impressions of luminous objects, and that they resemble them also in their apparent immobility when the eye is displaced by an external force. If this result (which I state with much diffidence, from having only my own experience in its favour) shall be found generally true by others, it will follow that the objects of mental contemplation may be seen as distinctly as external objects, and will occupy the same local position in the axis of vision, as if they had been formed by the agency of light.” Hence the impression of an image once conveyed to the senses, no matter how, whether by actual or illusory vision, is liable to renewal, “independently of any renewed application of the cause which had originally excited it,” and the image can be seen in that renewal “as distinctly as external objects,” for indeed “the revival of the fantastic figure really does affect those points of the retina which had been previously impressed.”